This lesson teaches you how to

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If your app needs to request location or receive permission updates, the
device needs to enable the appropriate system settings, such as GPS or Wi-Fi
scanning. Rather than directly enabling services such as the device's GPS,
your app specifies the required level of accuracy/power consumption and
desired update interval, and the device automatically makes the appropriate
changes to system settings. These settings are defined by the
LocationRequest
data object.

This lesson shows you how to use the
Settings Client
to check which settings are enabled, and present the Location Settings
dialog for the user to update their settings with a single tap.

Configure Location Services

In order to use the location services provided by Google Play Services and
the fused location provider, connect your app using the
Settings Client,
then check the current location settings and prompt the user to enable the
required settings if needed.

Apps that use location services must request location permissions. For this
lesson, coarse location detection is sufficient. Request this permission
with the uses-permission element in your app manifest, as shown
in the following example:

If the device is running Android 6.0 or higher, and your app's target
SDK is 23 or higher, the app has to list the permissions in the manifest
and request those permissions at run time. For more information, see
Requesting Permissions at Run Time.

Set Up a Location Request

To store parameters for requests to the fused location provider, create a
LocationRequest.
The parameters determine the level of accuracy for location requests. For
details of all available location request options, see the
LocationRequest
class reference. This lesson sets the update interval, fastest update
interval, and priority, as described below:

Update interval

setInterval()
- This method sets the rate in milliseconds at which your app prefers to
receive location updates. Note that the location updates may be faster than
this rate if another app is receiving updates at a faster rate, or slower
than this rate, or there may be no updates at all (if the device has no
connectivity, for example).

Fastest update interval

setFastestInterval()
- This method sets the fastest rate in milliseconds at which
your app can handle location updates. You need to set this rate because
other apps also affect the rate at which updates are sent. The Google Play
services location APIs send out updates at the fastest rate that any app
has requested with
setInterval().
If this rate is faster
than your app can handle, you may encounter problems with UI flicker or data
overflow. To prevent this, call
setFastestInterval()
to set an upper limit to the update rate.

Priority

setPriority()
- This method sets the priority of the request, which gives the Google Play
services location services a strong hint about which location sources to use.
The following values are supported:

PRIORITY_BALANCED_POWER_ACCURACY
- Use this setting to request location precision to within a city
block, which is an accuracy of approximately 100 meters. This is
considered a coarse level of accuracy, and is likely to consume less
power. With this setting, the location services are likely to use WiFi
and cell tower positioning. Note, however, that the choice of location
provider depends on many other factors, such as which sources are
available.

PRIORITY_HIGH_ACCURACY
- Use this setting to request the most precise location possible. With
this setting, the location services are more likely to use GPS
to determine the location.

PRIORITY_LOW_POWER
- Use this setting to request city-level precision, which is
an accuracy of approximately 10 kilometers. This is considered a
coarse level of accuracy, and is likely to consume less power.

PRIORITY_NO_POWER
- Use this setting if you need negligible impact on power consumption,
but want to receive location updates when available. With this
setting, your app does not trigger any location updates, but
receives locations triggered by other apps.

Create the location request and set the parameters as shown in this
code sample:

The priority of
PRIORITY_HIGH_ACCURACY,
combined with the
ACCESS_FINE_LOCATION
permission setting that you've defined in the app manifest, and a fast update
interval of 5000 milliseconds (5 seconds), causes the fused location
provider to return location updates that are accurate to within a few feet.
This approach is appropriate for mapping apps that display the location in
real time.

Performance hint: If your app accesses the
network or does other long-running work after receiving a location update,
adjust the fastest interval to a slower value. This adjustment prevents your
app from receiving updates it can't use. Once the long-running work is done,
set the fastest interval back to a fast value.

Get Current Location Settings

Once you have connected to Google Play services and the location services
API, you can get the current location settings of a user's device. To do
this, create a
LocationSettingsRequest.Builder,
and add one or more location requests. The following code snippet shows how
to add the location request that was created in the previous step:

Prompt the User to Change Location Settings

To determine whether the location settings are appropriate for the location
request, add an OnFailureListener to the Task object that validates the location settings. Then, check
if the Exception object passed to the onFailure() method is an instance of the ResolvableApiException class, which indicates that the settings
must be changed. Then, display a dialog that prompts the user for permission to
modify the location settings by calling startResolutionForResult().

The following code snippet shows how to determine whether the user's location
settings allow location services to create a LocationRequest, as well as how to ask the user for
permission to change the location settings if necessary: